Method and apparatus for measuring the quantity of plasma water removed during hemodialysis

Abstract

A graduated container (1) is connected both to a filtering compartment (10) of a dialyzer (9) and to the dialysis liquid circuit (8); the connection between the graduated container and the dialyzing liquid circuit being made through a chamber (2) into which extends a tube (6) connected to the dialyzing liquid circuit (8).

I claim: 
     
       1. A device for measuring a quantity of filtrate removed from a patient during hemodialysis, the filtrate being removed in a dialyzer upon passage of the filtrate from blood of the patient through a semipermeable membrane in a compartment, the compartment defining means for carrying a flow of dialyzing liquid along one side of the semipermeable membrane, and means for carrying a portion of the blood along an opposite side of the semipermeable membrane, a quantity of filtrate passing during dialysis from the portion of the blood to the dialyzing liquid, said device comprising: a second compartment operable as a filtering chamber, the second compartment also having a semipermeable membrane and means for carrying a portion of the blood along a side of the semipermeable membrane of the second compartment; and,   a graduated container connected to the filtering chamber at an opposite side of the semipermeable membrane from the blood, a quantity of filtrate passing during dialysis from the blood to the graduated container and accumulating therein, the quantity of filtrate accumulating in the graduated container being related to the quantity of filtrate removed from the blood and passing to the dialyzing liquid, whereby a total volume of filtrate removed from the blood is indicated by the graduated cylinder, said dialyzer defining a dialysis liquid path and a blood path, the graduated container also being fluidly connected to the dialysis liquid path, whereby the filtering chamber operates at equal pressure with the dialyzer.   
     
     
       2. The device of claim 1, wherein the semipermeable membranes are hollow tubes, the hollow tubes separating the dialyzing liquid from the blood in the dialyzer and separating the blood from a tube leading to the graduated container in the filtering chamber. 
     
     
       3. The device of claim 1, wherein the semipermeable membranes of the dialyzer and of the filtering chamber are hollow tubes carrying blood and are disposed in parallel along a flowpath for the blood, the dialyzer and the filtering chamber being hydraulically separate and  fluidly connected such that the filtering chamber and the dialyzer operate at equal pressures. 
     
     
       4. The device of claim 3, wherein the dialyzer and the filtering chamber are disposed in a single subdivided housing and are connected together by an opening across a dividing wall between the dialyzer and the filtering chamber. 
     
     
       5. The device of claim 3, wherein the hollow tubes of the filtering chamber remove about five percent as much filtrate as the dialyzer. 
     
     
       6. A device for measuring a quantity of plasma water removed from a patient's blood during a dialysis sitting by means of a dialyzer (9) having a dialyzing compartment (11), the device comprising: a filtering compartment (10) hydraulically separate from the dialyzing compartment (11);   a graduated container (1) subdivided into two chambers (2, 3) communicating with one another through an opening (5) defined in a dividing wall (4) between said two chambers, the graduated container (1) being closed by a cover (7) traversed (i) by a branch (16) of a tube (8) connecting the dialyzing compartment (11) of the dialyzer (9) to a suction means, said branch (16) being fitted with a tube (6) extending into one (2) of said two chambers (2, 3); and,   (ii) by a tube (15) connecting another (3) of said two chambers (2, 3) with the filtering compartment (10) of the dialyzer (9), whereby the filtering compartment and the dialyzing compartment operate at equal pressure.     
     
     
       7. A method for measuring a quantity of plasma water removed from a patient's blood during a dialysis sitting, the dialysis sitting including passing the blood through a dialysis chamber along a semipermeable membrane with a dialysis liquid disposed on an opposite side of the semipermeable membrane from the blood and controlling pressures of the blood and the dialysis liquid, respectively, filtrate being thereby passed from the blood into the dialysis liquid and being carried away, the method comprising the steps of: connecting a filtering chamber in parallel with the dialysis chamber, the filtering chamber also having a semipermeable membrane along one side of which the blood is passed;   collecting in a graduated container filtrate passing through the semipermeable membrane of the filtering chamber, a quantity of said filtrate as collected indicating a quantity of filtrate passed in the dialysis chamber from the blood to the dialysis liquid; and,   operating the filtering chamber and the dialysis chamber at equal pressures by connecting both said chambers to a common blood supply and pressurizing the graduated container at a pressure equal to that of the dialysis liquid.   
     
     
       8. The method of claim 7, comprising connecting the graduated container to a conduit carrying the dialysis liquid by a tube. 
     
     
       9. The method of claim 7, comprising connecting the graduated container to a conduit carrying the dialysis liquid by a hole in the graduated container leading to a compartment connected by a tube to the conduit carrying the dialysis liquid.